feat: add prometheus support

[entropidelic]

Linked to #94

This PR adds support for Prometheus metrics

• Add --metrics flag to CLI to install a prometheus metrics exporter.
• Add reth prefix layer
• Add p2pstream.disconnected_errors metric.

[mattsse]

oh wow, tysm for taking this on!

ref #94

before we rush anything here, I'd like to discuss what:

• the best crate for metrics for our use case is
• do we miss out on anything if we fully commit to prometheus, as I understood it the metrics crate is not limited to prometheus, right?

@onbjerg wdyt?

[codecov-commenter]

Codecov Report

Merging #474 (37e2b9b) into main (2b0f531) will decrease coverage by 0.57%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main     #474      +/-   ##
==========================================
- Coverage   73.67%   73.09%   -0.58%     
==========================================
  Files         240      241       +1     
  Lines       23523    24474     +951     
==========================================
+ Hits        17330    17890     +560     
- Misses       6193     6584     +391     

Impacted Files	Coverage Δ
bin/reth/src/cli.rs	0.00% <0.00%> (ø)
crates/net/eth-wire/src/p2pstream.rs	82.44% <0.00%> (-2.19%)	⬇️
crates/storage/db/src/abstraction/cursor.rs	86.66% <0.00%> (-13.34%)	⬇️
crates/net/discv4/src/lib.rs	50.70% <0.00%> (-11.31%)	⬇️
crates/net/discv4/src/config.rs	60.62% <0.00%> (-9.38%)	⬇️
crates/net/common/src/ban_list.rs	61.05% <0.00%> (-6.03%)	⬇️
crates/stages/src/pipeline.rs	90.15% <0.00%> (-5.28%)	⬇️
crates/stages/src/test_utils/test_db.rs	66.10% <0.00%> (-5.09%)	⬇️
crates/net/discv4/src/proto.rs	86.29% <0.00%> (-4.41%)	⬇️
crates/net/network/src/discovery.rs	56.00% <0.00%> (-4.00%)	⬇️
... and 39 more

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[onbjerg]

I think this is ok for now but I would be wary adding a dockerfile (and a docker-compose file) right now since those quickly turn into bikeshedding in my experience (see foundry churn on the dockerfile) and I would rather not think too much about release stuff at the moment. We should think about not only supporting prometheus at some point but this is an ok starting point, although it will probably be moved around a bit as the CLI evolves :)

So TL;DR think it's ok to merge the metric stuff but would prefer no dockerfile atm (defer to @mattsse on the metric added in the networking crate - maybe it fits better somewhere else)

[unbalancedparentheses]

Completely agree with @onbjerg comment. I was telling the same the @entropidelic. We will focus more on the metrics and we will remove the dockerfile

[entropidelic]

thanks @mattsse and @onbjerg for the feedback! The docker related files have been removed from the PR and it is ready for review now

[onbjerg]

lgtm, thanks! it will probably experience a bit of churn when config lands

[laibe]

having a Dockerfile would be great to have once reth is closer to stable release. Many el and cl clients include one (out of the top of my head geth, nethermind, teku, lighthouse)